To the Editor:
CORONAVIRUS disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 and is transmitted primarily through respiratory droplets, contact routes, and aerosol transmission. The selection of respiratory support for patients affected by COVID-19 must balance the clinical benefit of the intervention against the risks of nosocomial spread. Aerosol-generating procedures and nebulization have the potential for fugitive emissions and carry a higher risk of transmission of the virus to the surrounding environment and should be performed only when absolutely necessary in negative- pressure environments, with frequent air exchanges, under the care of highly trained personnel. It is advised to consider pressurized metered-dose inhalers and dry powder inhalers for aerosol drug delivery instead of nebulizers whenever feasible in COVID-19 patients.1 However, the nebulizer is irreplaceable in uncooperative patients, patients with life-threatening respiratory disease, and poor response to metered-dose inhaler with spacer. The nebulization of drugs with a jet nebulizer causes sideways leakage of exhaled air, and the distance increases with increasing lung injury, ranging from 45 cm to 80 cm.2
Some high-flow/high-velocity systems and closed positive- pressure systems have capabilities to add nebulized medications without an increased risk of particle dispersal. Placement of a viral filter in-line with a nebulizer likely decreases the risk for nosocomial or healthcare worker infection,3 but the efficiency of these filters in preventing the transmission and the magnitude of the risk of acquiring COVID-19 through filtered nebulizers are not fully known.
As we are in midst of the pandemic, many countries are facing deficiency of equipment and supplies. At All India Institute of Medical Sciences, Patna, India, we recognized the need for a viable solution for the delivery of aerosolized medications to patients with COVID-19. To address this objective, we modified a high-flow, nonrebreathing mask with an oxygen reservoir bag, which is readily available in a hospital setting (Fig 1 , A). Three valves included in this assembly were reversed to serve our purpose (Fig 1, B). The facemask was inverted in such a manner that the unidirectional expiration valve comes inside and works as a unidirectional inspiration valve. The unidirectional inspiratory valve attached to the reservoir bag is reversed and connected with a 22- mm connector in such a manner that it now works as a unidirectional expiration valve. Extra oxygen tubing is used to connect the nebulization chamber to the facemask. Tubing containing the nebulized drug aerosols is directly opened inside the mask, bypassing the oxygen reservoir bag (Fig 1, C). The oxygen reservoir bag acts as an expired air reservoir bag, from where expired air passes to central suction via a suction tube. This whole assembly acts as a closed system from which there are very few chances of exhaled air and aerosol dispersion to the surrounding environment during nebulization. This device combines the principle of nebulizer mask and reverse-valve high-flow oxygen mask. The following are various advantages of this modified reverse-valve, high-flow oxygen mask device:
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1
Preventive in aerosol dispersion during the nebulization of COVID-19 patients.
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2
Convertible to an oxygen therapy device by attaching oxygen tubing in place of nebulization tubing.
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3
Preventive in droplet dispersion during coughing and sneezing by the patient.
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4
Ease of assembling by modifying an easily available device.
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5
Usefulness in the post-COVID era for the containment of other respiratory infectious diseases like tuberculosis.
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6
Usefulness in low resource settings.
Fig 1.
(A) A high-flow, nonrebreathing mask with an oxygen reservoir bag. (B) Three-valve assembly. (C) Nebulizer tubing opened inside the mask bypassing the oxygen reservoir bag.
This is an indigenous device, and a better design based on these principles can be engineered in the future.
References
- 1.Ari A. Practical strategies for a safe and effective delivery of aerosolized medications to patients with COVID-19. Respir Med. 2020;167 doi: 10.1016/j.rmed.2020.105987. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Hui DS, Chan MT, Chow B. Aerosol dispersion during various respiratory therapies: A risk assessment model of nosocomial infection to health care workers. Hong Kong Med J. 2014;20(Suppl 4):9–13. [PubMed] [Google Scholar]
- 3.Ari A, Fink J, Harwood R, et al. Secondhand aerosol exposure during mechanical ventilation with and without expiratory filters: An in-vitro study. Indian J Respir Care. 2016;5:677–682. [Google Scholar]